104 



ELEMENTS OF STEUCTURAL BOTANY. 



Figf. 134. 



along the ground, it is trailing or prostrate ; and if, as in 



the runners of the Strawberry, it takes root on the lower 



side, then it is 

 creeping. Such a 

 shoot as the run- 

 ner of the Straw- 

 berry, which takes 

 root at a distance 

 from the parent 

 plant, is commonly 

 called a stolon. 

 150. Many weak stems raise themselves by clinging to 



any support that may happen to be within their reach. 



In some instances the stem itself winds 



round the support, assuming a spiral 



form, as in the Morning-Glory, the 



Hop, and the Bean, and is therefore 



distinguished as twining. In other 



cases the stem puts forth thread-like 



leafless branches called tendrils (Fig. 



134), which grasp the support, as in 



the Virginia Creeper and the Grape. 



In the Pea, the end of the extended 



mid-rib of the leaf is transformed into a 



tendril (Fig. 135). Sometimes the leaf- 

 stalks themselves serve the same purpose, as in the 



Clematis or Virgin's Bower. .In these cases the stems 



are said to climb. Our Poison Ivy climbs over logs, &c., 



by the aid of its aerial roots. 



The stems of wheat and grasses generally are known as 



Fig. 134. — Leaf and tendril of Grape-vine. 

 Fig. 136— Tendril of the Pea. 



Fif!. 135, 



